Process of making alkali-chromate solutions.



J.H.P=-AYNE. PROCESS OF MAKING ALKALI OHROMATE SOLUTIONS.

Patented Dec. 16, 1913.

' APPLICATION FILED AUG ZB, 1911.

amvewtoz /1 24 Peg/212 wi/imcooeo ent re era-res Ems PAYNE, 0F YORKTQWN, VIRGINIA, ASSIG'NOR To FRED E. GIGNOUX, OF GA-PE ELIZABETH, MAINE.

rnocnss or Maxine Ari-mtg Specificationof Letters ?atent.

- "MATE Patented Dec. 1 8, T913.

To all whom it may concern:

Be it known that I, JAM-ES H. PAYNE, a

citizen of the United States, residing at In the process of treating chromium ores referred to the sesquioxid of chromium of the ore unites with the alkali or alkaline earth element or elements and with oxygen from the heated gases, to form chromates soluble in water. The operation has heretofore been carried onin stationary reverberatory furnaces involving heavy labor expense and large consumption of fuel. Moreover the yield of soluble chromate from the ore so treated is seldom over 80 per cent. of the theoretical. I

The novelty of my invention consists essentially in the use of a particular form of furnace for the treatment of the ore and,

in the proportioning ofthe substances formingthe raw mixture by which a proper physical condition of the material is secured and maintained during the, fupnacing operation. Instead of a stationary furnace I- employ a rotating cylinder suitably lined,

slightly inclined toward the firing end. The

raw mixture is fed into the cylinderat the cool end and slowly works its way through to the firing end', being constantly agitated by the rotation of the cylinder, receiving its heat and oxygen from the heated gases and by proper regulation of the s 'eed of rotation of the cylinder and the con ition and temperature of the gasesforms at the point of incipient fusion into porous rounded or irregular shaped sint'ered masses ranging in size from that of coarse sand to nodules sev- These sintered' eral inches in diamter. masses or clinker-s contain under proper Solutions, of which the conditions from 90 to 95 per cent. of the soluble ohromates theoretically possible to be produced.

The drawing is a longitudinal elevation partly in section of an apparatus adapted to carry out my invention. I

In the drawing which is to be understood as illustrative merely. and not as in any way restricting the invention to the use of the particular apparatus shown, A represents a source of gaseous fuel supply here indicated,

as a gas producer from which a suitable pipe A A leads through an opening 13 in a movable firing hood 0 to the interior of the 4 cylinder D. The opening B is of larger diameter than the exterior diameter of the pipe A so as to permitjair to be drawn in to mix with the gas and support combustion. The firing end of the cylinder D is closed by the hood (1 and its other end opens into a chamber D from which leads the usual stuck or chimney D Arranged within the chamber D is a feeding device here shown 5 as a screw conveyer E arranged to discharge into the open end of the cylinder D, The conveyer should, of course, be protented against injury from heat in any con venient way as by a'water jacket. The conveyer E is supplied with the raw mixture bya second screw conveyer F which takes it from a bin G. H is a discharge spout for the clinker carried by the hood The cylinder D is supported on an inclination as shown, the firing end being lower than the other end, in the usual way .by roller bearings II I. on which rings I I rest and is rotated by means of a pinion K in mesh with a toothed ring K.

"The m xturefed to the rotating cylinder may consist of any of the well known mixtures used in the production of soluble chroof a properly proportioned raw mixture would be 100' parts chrome iron ore (50% Cr O 7O partssoda ash, and 100 parts quick lime.

It is essential that suificient lime or other refractory basic material beadded to prevent actual fusion during the furnacing operation because this invariably results in a low yield of soluble chromate. The point of incipient fusion must not be exceeded in order that the masses as they form may re main porous thereby insuring the entrance of the oxidizing gases in the furnacing operation and the leaching solutions in the subsequent leaching operation.

The raw mixture may be fed in the form of a slurry in which form a more intimate mixture of the ingredients than can be secured in a dry mixture, is made possible, thereby. producing a higher yield and reducing the tendency to ball up. The tendency to ball up is also lessened by the use of limestone in the mixture.

It is important that the gases be highly oxidizing and that they move at a speed. Any kind offuel may be used either gaseous or liquid or coal and oil, provided precautions are taken to burn them under oxidizing conditions with large excess of air.

It will, of course, be understood that the raw mixture is fed continuously into the end of the rotary cylinder and as the cylinder rotates the material will be constantly agitated'and by reason of the inclinationof the cylinder'will move toward the firin end and as-it moves toward the firing end wlll be subjected to an increased degree of heat. 1 It will, of course, be understood that the clinker formed in the furnacing operation above described is subsequently leached toextract the chromate.

high I Having thus described my invention what I claim is:

1. The process of making an alkali chromate solution which consists in passing a mixture of chrome iron ore, a basic refactory material and an alkaline material through an inclined rotary cylinder inadirection toward its' lower end against a current of ash through an inclined rotary cylinder inv a direction toward its lower end against a current of oxidizing gases moving toward the higher end of the cylinder, and heated'to a temperature such as to heat the mixture to a point not exceeding that of incipient fusion, and leaching the resultant porous nodules; i i

3. The process of making an alkali chromate solution which consists in passinga wet mixture of chrome iron ore, a basic re,- fractory material and an alkaline material through an inclined rotary cylinder in a current of; oxidizing gases moving toward direction toward its lower end against a the higher end of the cylinder and heated to p I,

a temperature such as to heat the mixture to a point not exceeding that of incipient fusion, and leaching the resultant porous nodules. Y

. Witnesses: v

GEORGE N. Wren, W. S. CAownLL.

' I JAMES PAYNE. 

